1. Field of the Invention
The present invention relates to flashlights and more specifically to flashlights having movable heads.
2. Related Art
Flashlights, such as that shown in U.S. Pat. No. 4,577,263, have movable heads to activate internal switch mechanisms or to focus the beam by longitudinal movement of the flashlight head relative to the barrel. In one configuration, when the head of the flashlight is fully threaded on the barrel, the switch mechanism is such that an electrical circuit through the batteries of the flashlight, through contacts between the batteries and the bulb and through the flashlight barrel, the tail cap and back to the batteries is open. As the head is threaded away from the barrel, the electrical circuit is closed, thereby passing current through the bulb to produce a light beam. As the head is further threaded away from the barrel, the head can ultimately be removed from the barrel, leaving the bulb exposed beyond the end of the barrel.
Though removal of the flashlight head provides an ambient light source, the bulb is easily damaged by only a small impact, thereby rendering the flashlight inoperable unless spare bulbs are readily available. To this end, manufacturers have provided a cavity in the tail cap of such flashlights for holding spare bulbs, but it can store only one. Therefore, the ability to use such a flashlight as an ambient light source is of questionable value.
With flashlights of the above-noted type made as pocket-sized flashlights, the barrel, head and tail cap are the main external components. Because these flashlights are to be placed in the pockets of clothing or purses, these portions of the flashlight should be substantially free of projections and sharp edges to minimize the possibility of catching fabric and thereby damaging the fabric. Thus, an internal switch is a desirable feature since external switch mechanisms may catch on a fabric Also, many flashlights which take AA-sized batteries include a tail cap having a hole bored through the end thereof for accepting a key ring or lanyard However, smaller flashlights accepting AAA-sized batteries would require a substantial amount of material in the tail cap to allow such a bored hole for accepting key-rings and lanyards Such additional material would add to the size and weight of the flashlight, which would be undesirable for pocket-sized flashlights.